1. Technical Field
The present invention relates to the use of laser emitted optical energy or radio frequency ("RF") energy for joining, repairing or reconstructing biological tissue. In particular, the present invention relates to a method of utilizing a collagen welding rod material in combination with such optical or RF energy as a filler to join, repair or rebuild biological tissue.
2. Background Art
Optical energy, in particular that generated by lasers, has been applied and utilized in the medical field for a variety of surgical purposes. The medical industry initially utilized industrial lasers for the destruction of tumors or surface lesions in patients. At that time, the lasers were relatively crude, high powered and ineffective for delicate internal biological applications.
Subsequently, a variety of cauterization techniques were developed utilizing either laser or RF techniques. Laser optical energy was also utilized to reduce the flow of blood in an open wound or in a surgically created incision: the optical energy being supplied in sufficient quantity to sear or burn the blood vessels thus sealing the open ends of the capillaries and preventing blood flow. A typical use of laser cauterization is described in U.S. Pat. No. 4,122,853. Again, the types of lasers utilized at that time provided very high power application and very high wattage with the surrounding tissue also being destroyed, thus causing longer healing times, infection and scarring.
As newer, lower powered lasers were developed, techniques were developed for atheroma ablation or other endarterectomy procedures for blood vessels. One such procedure is disclosed in U.S. Pat. No. 4,878,492. The CO.sub.2, YAG and Excimer lasers all provided substantial improvements in these procedures due to their lower power output. These more sophisticated devices each provide better aiming of a narrower optical energy beam such that destruction of the walls of the blood vessels can be minimized. Also, advances in optical fiber technology allowed the surgeon to conduct more accurately the optical energy to the desired location with greater precision.
Lasers have also been used to "glaze" the internal surfaces of blood vessels after balloon dilation and laser angioplasty in an attempt to prevent medical recollapse, intimal fibroplasia, and reobliteration.
Another procedure which has been developed includes the use of optical energy for welding or otherwise joining or connecting biological tissue. The original attempts to carry out these procedures began in the late 1960's and almost all universally met with failure not so much because of an inability to weld or join the tissue together, but because of the weakness of the resulting weld. The use of the lower powered laser devices, either alone or in combination with physiologic solutions, however, allowed the surgeon to cool the weld site sufficiently to obtain slight improvements in weld strength. Furthermore, RF energy has recently been utilized in both uni- and bi-polar generators to attempt to "weld" or "solder" biological tissue.
U.S. Pat. No. 4,672,969 discloses one method and apparatus for utilizing laser emitted optical energy to effect wound closure or other reconstruction of biological tissue by applying the optical energy to produce thermal heating of the biological tissue to degree suitable for denaturing the tissue proteins such that the collagenous elements of the tissue form a "biological glue" which seals the tissue to effect the joining. This glue is later reabsorbed by the body during the healing process. The patent discloses a number of different types of lasers with preference stated for the Nd:YAG type, because its particular wavelength allows optical energy to propagate without substantial attenuation through water and/or blood for absorption in the tissue to be repaired.
Despite these improvements, however, the weakness of the weld joint still remains as the primary disadvantage of this procedure and extensive current research is being conducted in an attempt to improve on that deficiency. I have now invented a simple yet elegant welding procedure for biological tissue utilizing laser or RF energy which overcomes the shortcomings of the prior art.